Echidna

(E-kid'-na). Half-woman, half-serpent. She was
mother of the Chimæra, the many-headed dog Orthos, the hundred-headed
dragon of the Hesperides, the Colchian dragon, the Sphinx, Cerberos,
Scylla, the Gorgons, the Lernæan hydra, the vulture that gnawed away
the liver of Prometheus, and the Nemean lion.

(Hesiod.)

[She] seemed a woman to the waist, and fair
But ended foul in many a scaly fold,
Voluminous and vast.